12.24. Docking Station / Port Replicator

12.24.1. Definitions

First some definitions. There is a difference between docking
station and port replicator.

I use the term docking station for a box which
contains slots to put some interface cards in, and space to put a
harddisk, etc. in. This box can be permanently connected to a PC. A
port replicator is just a copy of the laptop ports
which may be connected permanently to a PC.

12.24.2. Other Solutions

I don't use a docking station myself. They seem really expensive and I can't
see any usefulness. Alright you have to deal with some more cables, but is
it worth so much money? Docking stations are useful in an office
environment when you have a permanent network connection, or need the
docking station's expansion bus slots (e.g. for some excotic SCSI device).

Also all docking stations I know are proprietary models, so if you
change your laptop you have to change this device, too. I just found
one exception a docking station which connects to your laptop via
IrDA® the IRDocking IR-660 by
Tekram
. It supports these connectors: 10Base-T (RJ-45); PS/2 Keyboard; PS/2
Mouse; 25-Pin Printer Port (LPT); IR Transceiver; Power (6 VDC). So it
seems that a VGA port and a port to connect a desktop PC directly are
missing. This device should work with Linux/IrDA®, though I couldn't check it out.

I would prefer to buy a PC instead and connect it via
network to the laptop.

Or use an external display, which usually works well as described above,
and an external keyboard and mouse. If your laptop supports an extra
PS/2 port you may use a cheap solution a Y-cable,
which connects the PS/2 port to an external keyboard and an external
monitor. Note: Your laptop probably has support for the Y-cable
feature, e.g. the COMPAQ Armada 1592DT.

12.24.3. Docking Station Connection Methods

AFAIK there are four solutions to connect a laptop
to a docking station:

SCSI port (very seldom)

parallel port

(proprietary) docking port (common)

USB (often offered by third party manufacturers)

From Martin J. Evans
"The main problem with docking stations is getting the operating
system to detect you are docked. Fortunately,
you can examine the devices available in /proc
and thus detect a docked state. With
this in mind a few simple scripts is all you need to get your machine
configured correctly in a docked state.

You may want to build support for the docking station hardware as
modules instead of putting it directly into the kernel. This will save
space in your kernel but your choice probably largely depends on how
often you are docked.

1) Supporting additional disks on the docking
station SCSI card

To my mind the best way of doing this is to:

Either build support for the SCSI card into the kernel or build it as a module.

Put the mount points into /etc/fstab but use the
"noauto" flag to prevent them from being mounted automatically with the
mount -a flag. In this way, when you are docked you
can explicitly mount the partitions off any disk connected to the
docking station SCSI card.

2) Supporting additional network adaptors in the docking station

You can use a similar method to that outlined above for the graphics
card. Check the /proc filesystem in your rc scripts
to see if you are docked and then set up your network connections
appropriately. "

Once you determine this information, you may use a script, similar to
the following example, to configure the connection to your docking
station at startup. The script is provided by Friedhelm Kueck:

12.24.4. Universal USB Port Replicators

I have used a Typhoon USB 2.0 7in1 Docking Station made by
Anubis
P/N 83057 to check the Linux compatibility of such devices. Actually
this device should be named port replicator, because it does not have
any extension slots.
This device doesn't have a VGA port to connect to an external
display. Only a few USB docking stations have this feature. It would
be nice to get a report whether a VGA port works or not.
Tested with laptop COMPAQ M700 (USB 1.1) and custom made kernel 2.6.1.
Note the port replicator didn't work with
an Apple PowerBook G4.

How does its different ports work with Linux:

USB 2.0 A-type downstream: works with external hard disk and mouse out of the box

USB 2.0 A-type downstream: see above

PS/2 keyboard: works out of the box

PS/2 mouse: works, but for 2.6 Kernels you have to specifiy
the right mouse protocol psmouse_proto=imps
(if psmouse is compiled as a module).